Manufacture of sulphate of potash



sept. '22,A '1931. H. w. MORSE 1,824,361

MANUFACTURE OF SULPHATE OF POIASH Filed April 29. 1929 Patented Sept. 22, 1931 f vUNirai) sffrTEsf HARRY 4Waaraan MORSE, orrnnnwoon crrxcnmronmn ,MANUFACTURE ,or sULPHA'rEoFrO'rnsE y i v Application 'l'erd April` 29,V

This invention relates tothe' recovery of covered from the end liquor of Searles Lake brine.

A further object is to provide a process for otassium in the form of the recovery of v l p p w Glaserite, K3Na(O4)2`, from solutions containing potassium." 5"

Other objects will tion proceeds.

In the process of @Pref as.; the dass;

taining about 19%` of potassium chloride. This liquor is ,cooled forthe separation by crystallization 'of the aforementioned salts.

The resulting mother liquor contains about 10 to 11% of potassium chloride together' with sodium chloride, sodium carbonate, so-

dium sulphate and boraX.y This motherv liquor is sometimes returned to the evaporator-s whereit is miXedwith raw brine and reconcentrated. y

I have discovered va process for the recovery of the potassium contained in this mother f liquor, in the form of Glaserite, SO-Q2.

mother liquor mentioned above, anhydrous sodium sulphrategor a mixturecontainingsubstantial quantities of this salt, andagitate the solution for a relativelyj'short period,

In my application Serial No.'35`1,331,filed March 30, 1929, I disclose a process for. the separation of a double sulphate-carbonatepof sodium from Searles Lake brine; l VThis salt whereby potassium sulphate may be re- Y y y p `recovering.potassiumv 20' chloride and boraX. from Searles Lake brine, a hot concentrated liquor is producedicon# In carrying out'this process, I addto'the` u n y Y hours;V "Fromthelast chamberl, the mixture whereupon a precipitate of' crystals of'Glas 1929. j frsefiar No. 359,108.

has been found to have the followingfapproximate composition: lL Y I have found that if this double sulphate-carbonate is used insoli'd form instead of-anhydrous sodium sulphate, the same resultk is vsecured, although in this case the process may be somewhat less efiicient, with a smaller recovery of potassium. f l

have illustrated'somewhat conventionally'an arrangementt of apparatusl which Yis Well* Aztfkla'pted 'to carry out my'process. Itf coin- .prises-*1n general, 'a two` stage counter-cur- In .the accompanying sheet of drawing, I

renttreatment, motherliquor high in potas- -sium beingfcaused to reactfwith partially decomposed sulphate yor I sulphate-carbonate of sodium, and the intermediateliquor partly vexhausted' of its potassium lcontent `Abeing -f caused to react with fresh anhydrous 4sulphate or 'sulphate-'carbonate of sodium. Y

vMotherlliquor from the potassium chloride y 'and boraxgcrystalli'zing stage f ai conventionalV Searles Lake brine treating plantis introduced into the system through conduit'lO. Itisreceived'into a mixing chamber 12 where it is mixed with the intermediate solids,"

whose preparation will be presently described. In receptacles 12, la and 16, the mixture'of mother liquor and solid salts' is thoroughly agitated ata temperature' o f about 25 "Gg, for a periodofjapproximately V'two` of liquor and solid. salts flows through a conpipe22, whilethe thick v4sludge, comprising "about 50% water, passes through conduit`24 into the pan 26 of@J vacuum lter of conventionaltype. The rcrystals' are here sucked `as dryas possible on*y revolving drum 28, and

are removed therefrom at 3057Th`e liltrate'is removed through pipe 32, and is joined With the liquid from pipe 22 in a common intermediate liquor conduit 34. y

The solid salts collected on 30 consist of the .double sulphate of potassium and sodium K3Na(SO) 2' containing 384107Z KgO. This double salt may, of course, be used in any Way that may be desired, either directly in the form in Whichit is obtained as fertilizer, for example, or the potassium may be separated and used in a purified state.

The intermediate liquor which has lbeen removed from the .crystals is led through pipe 34 to Va second mixing chamber 36.

Here it is mixed With the anhydrous sodiumV sulphate previuslylmentioned, which 'l :haveshovvn conventionallyas introduced through conduit 89. The partially exhaustedmother liquor is thoroughly agitated with the solid salt in receptacles 36,38 and 40.' The tem- ,peraturepf the mixture islinaintained `at substantially 25o Cf.,-,an.dthe rateof flowis .souregulated that the material Willremain lintheagitatorseorabout two hours.` The ftransormationfromthe sulphate to double sulphatevis not complete at -this stage due to the :partiallyexhausted condition of the Y 'moth-er liquor. vBut bytreatingthezliquor.in

two stagesas haveoutlined, a .much more efficientseparation-ofzthe potassium from theV 4solutionis ,possible From the third chainherllO the mixture ofexhaustedanother liquor and solid salts Vpasses through. .a conduit 42 into a. ,thickenerV gita." l After.settling., thesupernatant liquid is .oit crystals passes through conduit k.418 .to vac- Lluum 'filter'50. vThe :clear liquor l@from this liltrlateisgled oilthroughpipe52 ivhiclrjoins `pipe416. A'This' end Eliquormay bereturned to. thefevaporatorsl forurther concentration or mayfberothelwise disposedvof. ItI vmay contain 1as littleasfLO per cent of KCl.

n .ber '.12 .Where theyv are moved V. With Vincoming. mother liquor, therebycompleting the cycle..

l The solids .from lilter fafter being Emoved at 152i, Qdrop into .alsalt .hopper56, by means of A'which xkthey' .are `conducted .to chamn Insteadof-using anhydrous s'odiumfsulv phate at 36, VI may, of desired,` as previously y '.indicatedi,..u se tthe @sulphatefcarbonate of" soassiuin chloride kconnot zreduce.tl ent of .the end liquqr to as lou7 a-,point asdoes .the sulphate. Either salt .oramixtureof thev tuo'in. any desired l,proportion may, however,

v loe used. .The term sodium'sulphate as used Iin' the-.appended.claimslis intended Vto, in-

clude either the pure ,orsubstantially pure4 -salltfolrza mixtureotthis salt Withothensalts,

in'gwhi'ch mixture sodium sulphate is present fin large' proportion.

l'Instead ofthemother liquor from a Searles Lalieghrine', any solution containing potas- ',sium chloridek .in concentration sufcient .to

`eidisadvantage ,thatit produce a precipitate of potassium sodium sulphate under the conditions as described, may be employed.

As an example of operation, which is to be considered as purely illustrative, I have found it possible to treat in twenty-four hours 1360 tons of motherliquor, containing 10 percent of KCl, in apparatus of the following approximate dimensions: Agitators 12, ltrand 16 may be 12 feet high, and 12 feet in diameter. Thickener or settler 2O may be 25 rfeet.,in diameter and `8 feet deep. Filter 27 iis of a capacity to handle 100 tons of solids, with an equal Weight of filtrate, in 24 hours. Agitators 36, 38 and 40 may be 1G feetzhi-g'h and -14Aeet inv diameter, and thickener 4 4lis SO feet ,in/diameter and 8 feet deep. Filter 50 -is-vcapahleof handling 125 tons of solids in .24 `hours. Under these conditions, 150tons of crude anhydrous NaZSO.; Will be `ediiitolthe system each 24' hours, and 100 :tons of .the double salt will he recovered.

The endliquor Will 'containabout 1,0 pei-.cent of KCl. y

Many changesin .the details ofprocedure could, ofcourse,-be.made.hy anyone familiar Withthe art. The apparatus which have illustrated conventionally is intended merely toshovvone example ofthemanner in .Which my process can loe carried out. lI therefore desire myinventionto .be limitedonlyloy gthe prior art `and the scope of the appended claims.

I claim: n

1. kAprocess for the recoveryofpotassium from a solution containingthesame, compriskingtreating said solutionv in lone stagefwith solidV partially reacted sodiumsulphate from .a second stage, separatinga double salt of hsodium andpotassium .sulphates from .the liquid, adding solid sodium sulphate to the liquid, alloWingsa-id sodi-um sulphate to ,react fvvith Vsaid solution lto form a precipitate )of ,sodium sulphate partially reacted with `liquid, allowing said sodium sulphate .to react vvithsaid solution to forma vprecipitate of Sodium sulphate `partially reacted `vvithrn` potassium sulphate, separating solid partiallyreactedsodium sulphate from the liquid,and addingsaidpartially reacted sodium sulphate. toa fresh ,supply of solution lin the first;stage.

forthe recovery of potassium l 3. A process for the recoveryof potassium from a solution containing the same, comprising treating said solution in one stage with solid partially reacted sodium sulphate from a second stage, separating a double salt of sodium and potassium sulphates from the: liquid, adding solid sodium sulphate to the liquid, allowing said sodium sulphate to re act With said solution at a temperature of substantially 25 C. to form a precipitate of L sodium sulphate partially reacted With potassium sulphate, separating solid partially reacted sodium sulphate from the liquid,and

adding said partially reacted 'sodium sul` phate to a fresh supply of solution in the first stage.

4. A process for the recovery of potassium from a solution containing the same, comprising treating said solution in one stage at a temperature of substantially 25 C. with solid partially reacted sodium sulphate from a second stage, separating a double salt of sodium and potassium sulphates from the liquid, adding solid sodium sulphate to the liquid, allowing said sodium sulphate to react With said solution Aat a temperature of substantially 25 C. to form a precipitate of sodium sulphate partially reacted With potassium sulphate, separating solid partially reacted sodium sulphate from the liquid, and adding said partially reacted sodium sulphate to a fresh supply of solution in the first stage.

HARRY WHEELER MORSE. 

